In a content managing device of the related art, a large number of digital content items are sorted and managed using methods such as a method in which the digital content items are stored at specified storage places in a state in which the digital content items are sorted into groups, a method in which additional information is added to the digital content items, and a method in which a desired content item is searched using the additional information. For example, when an example in which the digital content items are images is described, the variety of operations that users can perform using images, such as an operation of viewing images that were picked up by digital cameras, an operation of editing the images, an operation of printing the images, and an operation of placing the images in the public on a network, has increased in accordance with the widespread use of digital cameras and networks. Because of increase in the variety of operations, the users pick up a large number of images, and save the images in personal computers or the like. Accordingly, the need to manage the large number of images has increased.
In a typical content managing device of the related art, files in which content items are saved are arranged and managed by using folders having a layer structure as units of sets. FIG. 15 shows an example of a display screen illustrating content management that is performed with the typical content managing device of the related art. Referring to FIG. 15, for example, a folder having a name of “Sea” is generated. An image of sea (one type of content item) is selected, and dragged and dropped into the folder. In this manner, files of images related to sea can be sorted into the folder having a name of “Sea”. Furthermore, when it is desired to generate a new folder, a new empty folder is generated at first. Then, images that are desired to be sorted can be sorted into the folder by dragging and dropping. The sorted images can also be displayed in a sort-destination region corresponding to the folder.
For example, Japanese Patent Laid-Open No. 2005-276163 discloses that an image is displayed in a sort-destination region. A display format is disclosed in Japanese Patent Laid-Open No. 2005-276163. In the display format, there is a source view in which all images are displayed, and views corresponding to sort-destination regions are arranged at the upper side of the source view. A user selects an image from the source view, and drags and drops the image into one of the sort-destination regions (the views), thereby sorting the image. The dragged and dropped image is displayed in a small size in the view corresponding to the sort-destination region.
Furthermore, attribute information that can be utilized for a sorting task can be added to a sorted content item. FIG. 16 shows an example of a display screen in a case in which addition of attribute information to a content item is performed in the typical content managing device. A content item is selected, and properties are selected from the right-click menu, thereby a dialog box shown in FIG. 16 is displayed. Then, a keyword or a comment is input, whereby attribute information can be added to the content item.
Japanese Patent Laid-Open No. 5-165595 discloses that an operation of moving a tag to the side of cascaded pages of a document to add the tag to the document, thereby adding an identifier to the document.
However, in the related art, when it is desired to generate a new sort-destination region (for example, a folder), first, an operation needs to be performed to prepare an empty region. The operation that is performed to prepare an empty region is different from an operation that is performed to sort content items. For example, in Japanese Patent Laid-Open No. 2005-276163, when it is desired to generate a new view, it is necessary to generate an empty view by pressing a button that is provided at the side of the existing views. The operation of pressing a button to generate an empty view is different from an operation of dragging and dropping images to sort the images into views. Similarly, in the related art, an operation that is performed to prepare an empty region is different from an operation that is performed to add attribute information to content items. Accordingly, when a user sorts content items, the user needs to remember a large number of operations. Thus, a task of sorting content items with the content managing device is complicated and difficult particularly for a user who is not familiar with operations of a personal computer (PC) and who can only perform beginner-level operations.    Patent Citation 1: Japanese Patent Laid-Open No. 2005-276163    Patent Citation 2: Japanese Patent Laid-Open No. 5-165595